I'm a PC person, trying to help my daughter 2500 miles away listen to FLAC and MP3 files on her Mac (os X). While I'm knowledgeable about working with music files on a PC, I know little about Macs.

From googling, I pointed her at MacAmp lite. She tells me that it won't recognize most of the ogg/flac tags and ID3v2 tags I created with Tag&Rename, a commonly used PC program. It only sees a few of either that I created on the latest release of this tagging program. This mystifies me as they all show up on several PC and network players.

Is this problem inherent in a Mac or will Cog predictably read tags that MacAmp won't? Does she need a special tag plugin for either program?

Sorry to ask so basic of questions. If I had a Mac here I would just try it for myself. ..and yes, I'd rather have a Mac but I've got too much PC stuff to change at my age

Are you talking about "MacAmp Lite" or "MacAmp Lite X"?
MacAmp Lite is/was a MacOS application, it will not run natively in MacOSX, it may run in MacOSX Classic environment on PPC Macs.
MacAmp Lite X is/was a MacOSX application that died some (four?) years ago, not being able to compete with the all-dominant iTunes.